lua/json/encode/array.lua

   1 --[[
   2         Licensed according to the included 'LICENSE' document
   3         Author: Thomas Harning Jr <harningt@gmail.com>
   4 ]]
   5 local jsonutil = require("json.util")
   6
   7 local type = type
   8 local pairs = pairs
   9 local assert = assert
  10
  11 local table = require("table")
  12 local math = require("math")
  13 local table_concat = table.concat
  14 local math_floor, math_modf = math.floor, math.modf
  15
  16 local jsonutil = require("json.util")
  17 local util_IsArray = jsonutil.IsArray
  18
  19 local _ENV = nil
  20
  21 local defaultOptions = {
  22         isArray = util_IsArray
  23 }
  24
  25 local modeOptions = {}
  26
  27 local function mergeOptions(options, mode)
  28         jsonutil.doOptionMerge(options, false, 'array', defaultOptions, mode and modeOptions[mode])
  29 end
  30
  31 --[[
  32         Utility function to determine whether a table is an array or not.
  33         Criteria for it being an array:
  34                 * ExternalIsArray returns true (or false directly reports not-array)
  35                 * If the table has an 'n' value that is an integer >= 1 then it
  36                   is an array... may result in false positives (should check some values
  37                   before it)
  38                 * It is a contiguous list of values with zero string-based keys
  39 ]]
  40 local function isArray(val, options)
  41         local externalIsArray = options and options.isArray
  42
  43         if externalIsArray then
  44                 local ret = externalIsArray(val)
  45                 if ret == true or ret == false then
  46                         return ret
  47                 end
  48         end
  49         -- Use the 'n' element if it's a number
  50         if type(val.n) == 'number' and math_floor(val.n) == val.n and val.n >= 1 then
  51                 return true
  52         end
  53         local len = #val
  54         for k,v in pairs(val) do
  55                 if type(k) ~= 'number' then
  56                         return false
  57                 end
  58                 local _, decim = math_modf(k)
  59                 if not (decim == 0 and 1<=k) then
  60                         return false
  61                 end
  62                 if k > len then -- Use Lua's length as absolute determiner
  63                         return false
  64                 end
  65         end
  66
  67         return true
  68 end
  69
  70 --[[
  71         Cleanup function to unmark a value as in the encoding process and return
  72         trailing results
  73 ]]
  74 local function unmarkAfterEncode(tab, state, ...)
  75         state.already_encoded[tab] = nil
  76         return ...
  77 end
  78 local function getEncoder(options)
  79         options = options and jsonutil.merge({}, defaultOptions, options) or defaultOptions
  80         local function encodeArray(tab,  state)
  81                 if not isArray(tab, options) then
  82                         return false
  83                 end
  84                 -- Make sure this value hasn't been encoded yet
  85                 state.check_unique(tab)
  86                 local encode = state.encode
  87                 local compositeEncoder = state.outputEncoder.composite
  88                 local valueEncoder = [[
  89                 for i = 1, (composite.n or #composite) do
  90                         local val = composite[i]
  91                         PUTINNER(i ~= 1)
  92                         val = encode(val, state)
  93                         val = val or ''
  94                         if val then
  95                                 PUTVALUE(val)
  96                         end
  97                 end
  98                 ]]
  99                 return unmarkAfterEncode(tab, state, compositeEncoder(valueEncoder, '[', ']', ',', tab, encode, state))
 100         end
 101         return { table = encodeArray }
 102 end
 103
 104 local array = {
 105         mergeOptions = mergeOptions,
 106         isArray = isArray,
 107         getEncoder = getEncoder
 108 }
 109
 110 return array